One fine day in 1994, two policemen struggled up to the protest camp on Solsbury Hill, near Bath, and asked to be taken to the leaders. "You want to talk to Aqua and Sulis," someone told them. "They're up the top. You'll recognise them 'cos they're both black." The officers sweated up to the top of the hill and told the people there who they wanted to talk to. Everyone stared at them. "Aqua and Sulis? You sure about that?" they asked. "Definitely," the policemen replied. And so they were taken to meet the two black piglets that were kept as pets at the camp.

No one returned from Solsbury Hill unchanged. The battle against Batheaston bypass was a turning point in the fight against the government's road building programme, and in the lives of many of the people who became involved in it.

The protest - the first camp was set up on February 20, 1994 - began at a critical moment, when a raw, uncertain movement had begun to coalesce and find its voice. People emerged at the other end with a sense that life was richer - with experience and possibility - than they had imagined.

Under Margaret Thatcher, the government had decided to build a network of new motorways and trunk roads in order to realise her dream of universal driving. Hers was a programme not just to facilitate car ownership, but also to close down the alternatives.

We fought for Solsbury Hill because of what it was, what it represented. It was one of the few quiet places in a corner of England that was becoming ever noisier; a scene of slow beauty, of rough pasture, elder coverts and dense hedges, capped with an ancient hill fort. It epitomised the places we were losing to development in every county. Some protesters were local, the rest came from all over the country.

Draconian laws

When the first bedraggled refugees from Tory Britain arrived at Solsbury, they were still ahead in the arms race. The police, bailiffs and private security guards had not yet learnt how to extract people easily from the trees and their machinery. Nor had the draconian laws that would have made the whole protest illegal - the Criminal Justice Act, passed at the end of 1994, the 1997 Protection from Harassment Act or the 2005 Serious Organised Crime and Police Act - yet been passed. Britain, to an extent perhaps forgotten today, was still free.

The first permanent arrivals at the camp built simple shelters of hazel sticks and canvas on the ground, as well as rudimentary treehouses as high as they dared to live. At times, the place looked more like a circus than a protest camp. Indeed, three of the tree dwellers went on to become professional acrobats.

This was "green politics" at its most primeval and real. In an age when environmentalists are now likely to be wearing suits, it can be hard to imagine a time in which being "green" was not a fashionable metropolitan accessory but a political choice that set you apart from the reasonable majority.

Solsbury leaves us with lessons. Some of today's office-bound environmentalists, talking of parts per million of carbon and the importance of "sustainable development", would do well to remember that green politics, if it means anything, is born from a love of the natural world, and that a love of the natural world is fostered by being part of it. A sense of place, the smell of a night fire and the sensation of rain leaking through the roof of a bender are better guides to what is right and wrong than any number of policy papers.

We lost the fight over Solsbury Hill, and Bath has been left with a high-spec dual carriageway to nowhere. But building our way out of congestion and pollution is now a discredited idea, and for this the campaigners of Solsbury Hill can claim some responsibility. In that respect, at least, victory was ours.

• An exhibition based on the book will be held at Walcot Chapel gallery, Bath, from 17-28 February. Details at solsburyhill.org.uk

Life-Changing experiences: The protesters' tales

Indra

The locals asked us to come, and I was on the last bus to roll out. I had never heard the words capitalism or particulates, but Solsbury attracted brilliant people who taught each other. It looked as if we were trying to save a few trees, but it was much more than that. It was the first protest where people lived in the trees. Throwing ourselves against machines was all we knew. It was the most profound and powerful experience in my life. When it finished, there could be no turning back. When you know what's happening to the world, or who is doing the damage, it's painful not to do anything. I've been working as a community development worker on a rundown estate in Brighton. Now I am the co-ordinator for a Travellers' schools charity. My children go to the climate camp. My 18-year-old takes herself to marches and camps. I am so proud of them.

Nick Pepper

I spent six months at Solsbury and it empowered me massively. It was the seed for all the other protests that followed. I carried on protesting for 10 years, then went to Australia. I ended up 60 metres up a tree there and we stopped old-growth logging. Now I am back and have been part of a group trying to stop the Weymouth relief road. I have been working as a rigger and a climber, but I am now going to do a woodland management course. I am an ecologist, but I am classed as an enemy of the state. I just feel sorry for the police forward intelligence team who still follow me round. What a waste of their time!

Jerry

Solsbury defined my life for many years. I gave up a law degree to go there - went for a weekend, then another, and then I stayed. We were a mixture of the homeless and jobless. There was a massive pool of people waiting for something to happen. There are parallels with today. The lesson from it is that is you have to force the changes in Britain. I still see government pandering to the environment. The government still has to be dragged. After 10 years of protest, I had no possessions at all. In 2002, I went to Amsterdam and bought a wooden ship and restored it. I shall bring her back to Britain, get involved again, and set up a party for all the people who do not vote. We need to do an Obama!

Cathy Jordan

I was a local. I lived in Balebrook on the side of Solsbury Hill. It's a totally different place now. It was a haven, but now the countryside has been pushed back. I am completely different, too. Before the road came, I was politically naive. It changed me completely. I learned about how things work. I had not thought how decisions are made. I now see the government was taking the mickey. The public inquiry was there to shut people up. It's only when good, honest, normal people get together and say "This is stupidity" that things change. It's madness what is happening now. Ordinary people must stand up and say no. We stood up. We were ordinary. Now I lobby and write and get involved in other campaigns.Interviews by John Vidal